End shield and inner bearing cap assembly

ABSTRACT

An explosion proof motor including a stationary assembly and a rotatable assembly is described. The stationary assembly includes a stator that defines a stator bore. The rotatable assembly includes a rotor and a rotor shaft extending substantially axially through the stator bore. The explosion proof motor includes a frame configured to at least partially surround the stator. The frame defines an interior and an exterior of the motor. The explosion proof motor also includes at least one end shield positioned at an end of the frame and a bearing cap positioned proximate to the interior side of the end shield. The explosion proof motor also includes a flame path gap defined between the end shield and the bearing cap. The flame path gap includes at least one section that extends substantially parallel to the rotor shaft.

BACKGROUND OF THE INVENTION

The field of the invention relates generally to electric motors, andmore specifically, to an end-shield and inner bearing cap assembly foruse in an explosion proof electric motor.

The National Fire Protection Association (NFPA) publishes codes andstandards, with the mission to minimize the possibility and effects offire and other events. One NFPA standard is Standard No. 70, theNational Electrical Code. Article 100 of Standard No. 70 includes ageneral definition of an explosion proof apparatus. Article 100 definesan explosion proof apparatus as, an “[a]pparatus enclosed in a case thatis capable of withstanding an explosion of a specific gas or vapor thatmay occur within it and of preventing the ignition of a specified gas orvapor surrounding the enclosure by sparks, flashes, or explosion of thegas or vapor within, and that operates at such an external temperaturethat a surrounding flammable atmosphere will not be ignited thereby.”The explosion proof designation does not ensure that an apparatus isincapable of exploding, but rather that the apparatus is capable ofwithstanding an explosion without causing damage to the apparatus'surroundings beyond a certain level.

Flame paths positioned between a motor end shield and an inner bearingcap are known to minimize external damage in the event of an electricmotor explosion. Another safety organization, Underwriters Laboratories(UL), publishes minimum requirements that must be met before receiving aUL rating. One minimum requirement established by UL for explosion proofmotors is a minimum length of a flame path defined between a motor endshield and an internal bearing cap. Meeting/exceeding the minimum flamepath length may prevent motor size reduction and/or limit the sizes ofbearings that may be included in a motor.

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, an explosion proof motor including a stationary assemblyand a rotatable assembly is provided. The stationary assembly includes astator that defines a stator bore. The rotatable assembly includes arotor and a rotor shaft extending substantially axially through thestator bore. The explosion proof motor includes a frame configured to atleast partially surround the stator. The frame defines an interior andan exterior of the motor. The explosion proof motor also includes atleast one end shield positioned at an end of the frame and a bearing cappositioned proximate to the interior side of the end shield. Theexplosion proof motor also includes a flame path gap defined between theend shield and the bearing cap. The flame path gap includes at least onesection that extends substantially parallel to said rotor shaft.

In another aspect, a method for assembling an explosion proof motor isprovided. The explosion proof motor includes a rotor and a rotor shaftpositioned at least partially within an interior of a stator bore. Therotor shaft extends axially through the stator bore. The method includespositioning a bearing cap around the rotor shaft and positioning abearing around the rotor shaft and proximate to the bearing cap. Themethod also includes positioning an end shield proximate to the bearingand the bearing cap, wherein a flame path gap is defined between thebearing cap and the end shield. The flame path gap includes at least onesection that extends substantially parallel to the rotor shaft.

In yet another aspect, an end shield and inner bearing cap assembly foran explosion proof motor is provided. The assembly includes an endshield and an inner bearing cap. The inner bearing cap is positionedproximate to the end shield. The end shield and the bearing cap includeshaft openings extending substantially axially therethrough. Theassembly also includes a flame path gap defined between the end shieldand the bearing cap. The flame path gap includes at least one sectionthat extends substantially parallel to said axial shaft openings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of an electric motor assembly.

FIG. 2 is a partial cross-sectional view of an upper half of a knownelectric motor.

FIG. 3 is an expanded view of a portion of the electric motor shown inFIG. 1.

FIG. 4 is a partial cross-sectional view of an upper half of an electricmotor that includes an exemplary end shield and inner bearing capassembly.

FIG. 5 is an expanded view of a portion of the electric motor shown inFIG. 4 illustrating flame paths therein.

FIG. 6 is a partial cross-sectional view of an alternative embodiment ofthe end shield and inner bearing cap assembly shown in FIG. 5.

FIG. 7 is a partial cross-sectional view of another alternativeembodiment of the end shield and inner bearing cap assembly shown inFIG. 5.

FIG. 8 is a partial cross-sectional view of yet another alternativeembodiment of the end shield and inner bearing cap assembly shown inFIG. 5.

FIG. 9 is a partial cross-sectional view of another alternativeembodiment of the end shield and inner bearing cap assembly shown inFIG. 5.

FIG. 10 is a flowchart of an exemplary method for assembling anexplosion proof motor.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is an exploded view of an electric motor assembly 10. Electricmotor assembly 10 includes a stationary assembly 14 that includes astator or core 16. Electric motor assembly 10 also includes a rotatableassembly 18 that includes a rotor 20 and a shaft 22. A fan (not shown)or other means to be driven such as means for moving air through an airhandling system engages shaft 22. Specifically, motor assembly 10 is foruse in applications where hazardous fumes or dust may be present.

Rotor 20 is mounted on shaft 22 journaled for rotation in bearings 24and 26. End shields 32 and 34 are substantially parallel to each other.End shields 32 and 34 have inner facing sides 36 and 38 between whichstationary assembly 14 and rotatable assembly 18 are located. Each endshield 32 and 34 has an outer side 40 and 42 opposite its inner side 36and 38. Additionally, first end shield 32 has an aperture 44 for shaft22 to pass through and extend out from outer side 40. Second end shield34 has an aperture 46 for the shaft 22 to pass through and extend outfrom the outer side 42. End shields 32 and 34 are coupled to a motorhousing 48 that surrounds stationary assembly 14 and rotatable assembly18.

Electric motor assembly 10 also includes inner bearing caps 50 and 52.Inner bearing caps 50 and 52 include openings 56 and 58 through whichshaft 22 passes through. Inner bearing caps 50 and 52 are configured tobe coupled to first end shield 32 and second end shield 34,respectively. Bearing 26 is secured between first end shield 32 andinner bearing cap 50. Bearing 24 is secured between second end shield 34and inner bearing cap 52.

FIG. 2 is a partial cross-sectional view of an upper half of a knownelectric motor 100. Electric motor 100 includes a stationary assembly110 including a stator core 112 and a rotatable assembly 120. Rotatableassembly 120 includes a rotor 122 and a shaft 124. Electric motor 100also includes end shield and inner bearing cap assemblies 126 and 128.End shield and inner bearing cap assembly 126 includes an end shield 140and an inner bearing cap 142. End shield and inner bearing cap assembly128 includes an end shield 144 and an inner bearing cap 146.

Rotor 122 is mounted on and secured to shaft 124 journaled for rotationin bearings 148 and 150. Bearing 148 is positioned between end shield140 and inner bearing cap 142. Similarly, bearing 150 is positionedbetween end shield 144 and inner bearing cap 146. End shields 140 and144 are substantially parallel to each other and coupled to a motorframe 152 to define an interior 154 and an exterior 156 of motor 100.End shields 140 and 144 have inner facing sides 160 and 162 betweenwhich stationary assembly 110 and rotatable assembly 120 are located.Each end shield 140 and 144 has an outer side 164 and 166 opposite itsinner side 160 and 162. Additionally, end shield 144 includes anaperture 170 for shaft 124 to pass through and extend out from outerside 166. Although described herein as end shields 140 and 144, endshields 140 and 144 may also be referred to as end members and/or endcaps. Rotor 122 includes a core 180 and is rotatable within a bore 182of stator 112. Stationary assembly 110 includes a plurality of windingstages 184 adapted to be electrically energized to generate anelectromagnetic field.

Electric motor 100 also includes a first flame path gap 190 and a secondflame path gap 192. First flame path gap 190 is defined as an interfacebetween end shield 140 and inner bearing cap 142. Second flame path gap192 is defined as an interface between end shield 144 and inner bearingcap 146. Flame path gaps 190 and 192 each have a length 194, measuredfrom an outer edge 196 of bearing 148 and 150 to an outer edge 198 ofinner bearing caps 142 and 146. Certain applications for motor 100require length 194 meet or exceed a defined value in order to receive anorganization provided label. For example, Underwriters Laboratories(UL), publishes minimum requirements that must be met before receiving aUL rating. In order to obtain the UL designation as an “explosion proof”motor, the motor may be required to include a flame path gap exceeding aminimum length.

Stator bore 182 has an inner radius 200, measured from a center 202 ofshaft 124 to an inner edge 204 of stator 112. Inner bearing caps 142 and146 have an outer radius 210, measured from center 202 of shaft 124 toouter edge 198 of inner bearing caps 142 and 146. Assembly techniquesthat include passing inner bearing cap 142 or inner bearing cap 146through stator bore 182 are not possible because radius 210 is greaterthan radius 200. In order to maintain flame path gap length 194, whilereducing radius 210 of inner bearing cap 142, a smaller bearing 148 maybe selected. In typical motor assembly processes, only one of innerbearing caps 142 and 146 is passed through stator bore 182. A largerbearing provides benefits such as, but not limited to, increasingbearing life and reducing vibration. However, in known motors, tofacilitate passing one of inner bearing caps 142 and 146 through statorbore 182 during assembly, a smaller bearing is included on one side ofmotor 100.

FIG. 3 is an expanded view of a portion of electric motor 100 (shown inFIG. 2). More specifically, FIG. 3 is an expanded view of a portion ofend shield and inner bearing cap assembly 128, shaft 124, and bearing150. Flame path gap 192 is defined between end shield 144 and innerbearing cap 146. Flame path gap 192 is substantially radially alignedwith respect to shaft 124 and has length 194 extending from outer edge196 of bearing 150 to outer edge 198 of inner bearing cap 146. Endshield and inner bearing cap assembly 126, and therefore flame path gap190 (shown in FIG. 2), are configured in a substantially similar mannerto end shield and inner bearing cap assembly 128 and flame path gap 192,on an opposite side of motor 100.

FIG. 4 is a partial cross-sectional view of an upper half of anexemplary embodiment of an electric motor 300 that includes a firstflame path gap 302 and second flame path gap 304, each having asubstantially radial section 310 and a substantially axial section 320.Components shared between electric motor 300 and electric motor 100(shown in FIG. 2) are identified with the same reference numerals. Inthe exemplary embodiment, electric motor 300 includes end shield andinner bearing cap assemblies 326 and 328. In the exemplary embodiment,end shield and inner bearing cap assembly 326 includes a first endshield 330 and an inner bearing cap assembly 332. In the exemplaryembodiment, end shield and inner bearing cap assembly 328 includes asecond end shield 334 and an inner bearing cap 336. First end shield 330includes a flame path tab 338 and second end shield 334 includes a flamepath tab 340. Flame path tabs 338 and 340 are axial protrusionsextending from end shields 330 and 334 toward stator bore 182. In theexemplary embodiment, inner bearing cap 332 is positioned around shaft124 and extends toward flame path tab 338. Inner bearing cap 336 ispositioned around shaft 124 and extends toward flame path tab 340. Shaft124 extends through openings 360 and 362 in inner bearing caps 332 and336. Bearings 370 and 372 are secured between inner bearing caps 332 and336 and end shields 330 and 334, respectively. More specifically,bearings 370 and 372 are secured within bearing pockets 374 and 376.Bearing pocket 374 is defined by end shield 330, inner bearing cap 332,and shaft 124. Bearing pocket 376 is defined by end shield 334, innerbearing cap 336, and shaft 124.

FIG. 5 is an expanded view of a portion of electric motor 300 shown inFIG. 4. More specifically, FIG. 5 is an expanded view of end shield andinner bearing cap assembly 328, shaft 124, and bearing 372. In theexemplary embodiment, flame path gap 304 is defined between end shield334 and inner bearing cap 336. As described above, flame path gap 304includes radial section 310 and axial section 320. Radial section 310extends substantially radially from shaft 124 and has a radial length380. Radial length 380 is measured from outer surface 196 of bearing 372to an outer edge 384 of inner bearing cap 336. Axial section 320 extendssubstantially axially with respect to shaft 124 and has an axial length390. Radial section 310 extends substantially perpendicular to shaft 124and axial section 320 extends substantially parallel to shaft 124. Morespecifically, axial section 320 is defined between a shaft-side edge 394of flame path tab 340 and outer edge 384 of inner bearing cap 336. Axiallength 390 is measured from an inner edge 396 of end shield 334 andeither an inner edge 398 of flame path tab 336 or an inner edge 400 ofinner bearing end cap 336, whichever is closer to inner edge 396 of endshield 334.

In the exemplary embodiment, axial length 390 is less than radial length380. A total length of flame path gap 304 is radial length 380 inaddition to axial length 390. In the exemplary embodiment, the totallength of flame path gap 304 is equal to or greater than length 194 offlame path gap 192 (shown in FIG. 3). However, by including radialsection 310 and axial section 320, inner bearing cap 336 has a radius410 that is smaller than radius 210 (shown in FIG. 2) of inner bearingcap 146 (shown in FIG. 2), while maintaining a flame path gap length. Inthe exemplary embodiment, end shield and inner bearing cap assembly 326(shown in FIG. 4) is configured substantially similarly to end shieldand inner bearing cap assembly 328.

Referring once again to FIG. 4, radius 410 of inner bearing caps 332 and336 is smaller than radius 186 of stator bore 182. Radius 410facilitates assembly processes that include passing inner bearing cap332 or inner bearing cap 336 through stator bore 182, while maintaininga total length of flame path gap 302 and/or 304.

FIG. 6 is a partial cross-sectional view of an alternative embodiment500 of end shield and inner bearing cap assembly 328 (shown in FIG. 5).Like end shield and inner bearing cap assembly 328, end shield and innerbearing cap assembly 500 may be included in electric motor 300 (shown inFIG. 4). End shield and inner bearing cap assembly 500 includes an endshield 502 and an inner bearing cap 504. A flame path gap 506 is definedbetween end shield 502 and inner bearing cap 504. In the exemplaryembodiment, flame path gap 506 includes a substantially radial section510 and a substantially axial section 520. Although substantially radialsection 510 is illustrated as being angled toward interior 154 (shown inFIG. 4) of electric motor 300, substantially radial section 510 may alsobe angled toward exterior 156 (shown in FIG. 4) of electric motor 300.

FIG. 7 is a partial cross-sectional view of another alternativeembodiment 600 of end shield and inner bearing cap assembly 328 (shownin FIG. 5). Like end shield and inner bearing cap assemblies 328 and500, end shield and inner bearing cap assembly 600 may be included inelectric motor 300 (shown in FIG. 4). End shield and inner bearing capassembly 600 includes an end shield 602 and an inner bearing cap 604. Aflame path gap 606 is defined between end shield 602 and inner bearingcap 604. In the exemplary embodiment, flame path gap 606 includes only asubstantially axial section 620. In the exemplary embodiment, axialsection 620 has a length 624. Inner bearing cap 604 may be clampedtightly, also referred to as “locked,” to an outer race 626 of bearing372. In the exemplary embodiment, inner bearing cap 604 is positioneddirectly adjacent to bearing 372 (i.e., no space between inner bearingcap 604 and bearing 372). Eliminating a radial flame path gap sectionfacilitates locking inner bearing cap 604 to bearing 372 whilemaintaining a flame path gap. It is not possible on explosion proofmotor designs that include a radial flame path gap to lock the bearingcap to the bearing, since in order to maintain a radial flame path gap,the bearing cap must be clamped tightly to the end shield.

FIG. 8 is a partial cross-sectional view of yet another alternativeembodiment 700 of end shield and inner bearing cap assembly 328 (shownin FIG. 5). Like end shield and inner bearing cap assemblies 328, 500,and 600, end shield and inner bearing cap assembly 700 may be includedin electric motor 300 (shown in FIG. 4). End shield and inner bearingcap assembly 700 includes an end shield 702 and an inner bearing cap704. A flame path gap 706 is defined between end shield 702 and innerbearing cap 704. In the exemplary embodiment, flame path gap 706includes a plurality of substantially radial sections 710, 712, and 714and a plurality of substantially axial sections 716 and 718. In theexemplary embodiment, flame path gap 700 is a step shaped gap definedbetween end shield 702 and inner bearing cap 704.

FIG. 9 is a partial cross-sectional view of another alternativeembodiment 800 of end shield and inner bearing cap assembly 328 (shownin FIG. 5). Like end shield and inner bearing cap assemblies 328, 500,600, and 700, end shield and inner bearing cap assembly 800 may beincluded in electric motor 300 (shown in FIG. 4). In the exemplaryembodiment, end shield and inner bearing cap assembly 800 includes anend shield 802 and an inner bearing cap 804. A flame path gap 806 isdefined between end shield 802 and inner bearing cap 804. In theexemplary embodiment, flame path gap 806 includes a plurality ofsubstantially radial sections 810 and 812 and a single substantiallyaxial section 814. In the exemplary embodiment, flame path gap 806 is astep shaped gap defined between end shield 802 and inner bearing cap804.

FIG. 10 is a flowchart 900 of an exemplary method 910 for assembling anexplosion proof motor. In the exemplary embodiment, the explosion proofmotor assembled using method 910 includes a rotor and a rotor shaftpositioned at least partially within an interior of a stator bore. Forexample, method 910 may be used to assemble motor 300 (shown in FIG. 4),which includes rotor 122 (shown in FIG. 4) and rotor shaft 124 (shown inFIG. 4). Rotor shaft 124 extends axially through a stator bore, forexample, stator bore 182 (shown in FIG. 4). In the exemplary embodiment,method 910 includes positioning 920 a bearing cap, for example, bearingcap 336 (shown in FIG. 4), around rotor shaft 124. Method 910 alsoincludes positioning 922 a bearing, for example, bearing 372 (shown inFIG. 4), around rotor shaft 124 and adjacent to bearing cap 336. Method910 also includes positioning 924 an end shield, for example, end shield334 (shown in FIG. 4) adjacent to bearing 372 and bearing cap 336.Positioning 924 end shield 334 adjacent to bearing cap 336 includesdefining a flame path gap, for example flame path gap 304 (shown in FIG.4) between bearing cap 336 and end shield 334. In the exemplaryembodiment, flame path gap 304 includes at least one substantially axialsection, for example, axial section 320 (shown in FIG. 4).

In some embodiments, positioning 924 end shield 334 adjacent to bearing372 and bearing cap 336 includes securing end shield 334 and bearing cap336 along rotor shaft 124 to also define at least one substantiallyradial section, for example, radial section 310 (shown in FIG. 4), offlame path gap 304. In some embodiments, substantially radial section310 of flame path gap 304 extends substantially radially outward fromrotor shaft 124, and substantially axial section 320 of flame path gap304 extends substantially axially between end shield 334 and a statorbore, for example, stator bore 182 (shown in FIG. 4). In someembodiments, method 910 also includes securing bearing cap 336 tobearing 372. More specifically, including a flame path gap that is fullyaxially aligned, for example, flame path gap 606 (shown in FIG. 7),facilitates securing a bearing cap to a bearing, for example bearing cap604 to bearing 372 (shown in FIG. 7), while maintaining flame path gap606.

The electric motor described above includes a rotor positioned within astator, and an end shield and an inner bearing cap assembly. Theapparatus and methods described herein are not limited to use with amotor, but rather, the end shield and inner bearing cap assembly may beincluded within any type of rotating device that includes a shaft and abearing. Furthermore, although substantially linear flame path gaps aredescribed herein, non-linear flame path gaps, or portions of flame pathgaps, may also be defined within end shield and inner bearing capassemblies and function as described herein with respect to the linearflame path gaps. Additionally, combinations of the flame paths describedherein may be defined between an end shield and an inner bearing cap andfunction substantially similarly to the embodiments described herein.

The above-described end shield and inner bearing cap assemblies arereliable and cost-effective. The end shield and inner bearing capassemblies, and more specifically the flame path gaps defined betweenthe end shields and the inner bearing caps, facilitate use of thelargest possible bearing on both ends of the motor by minimizing thediameter of the bearing cap while maintaining a flame path gap length.By way of non-limiting example, an example motor may traditionally use afirst bearing on the drive-end and a second, smaller bearing on theopposite-end. The end shield and inner bearing cap assemblies describedherein facilitate using the first, larger bearing on both ends of themotor. Including the same sized bearing on both ends of the motorfacilitates standardizing the same bearing and bearing cap for both endsof the rotor assembly, increasing bearing life for the opposite-endbearing (larger bearings typically provide greater load capacity),increasing shaft extension diameter capacity for the opposite-end,reducing bearing vibration, and allowing locking of the bearing outerrace to the inner bearing cap. As a result, the end shield and innerbearing cap assemblies described herein are part of a cost-effective andreliable motor.

Exemplary embodiments of apparatus and methods for manufacture of amotor are described above in detail. The apparatus and methods are notlimited to the specific embodiments described herein, but rather,components of the apparatus and/or steps of the methods may be utilizedindependently and separately from other components and/or stepsdescribed herein. For example, the apparatus and methods are not limitedto practice with only the electric motor described herein. Rather, theexemplary embodiment can be implemented and utilized in connection withmany other rotary device applications.

Although specific features of various embodiments of the invention maybe shown in some drawings and not in others, this is for convenienceonly. In accordance with the principles of the invention, any feature ofa drawing may be referenced and/or claimed in combination with anyfeature of any other drawing.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

1. An explosion proof motor comprising a stationary assembly and arotatable assembly, said stationary assembly comprising a statordefining a stator bore, said rotatable assembly comprising a rotor and arotor shaft extending substantially axially through said stator bore,said explosion proof motor comprising: a frame configured to at leastpartially surround said stator, said frame defining an interior and anexterior of said motor; at least one end shield positioned at an end ofsaid frame; a bearing cap positioned proximate to the interior side ofsaid end shield; and a flame path gap defined between said end shieldand said bearing cap, said flame path gap comprising at least onesection that extends substantially parallel to said rotor shaft.
 2. Anexplosion proof motor in accordance with claim 1, wherein said flamepath gap further comprises at least one section that extendssubstantially perpendicular to said rotor shaft.
 3. An explosion proofmotor in accordance with claim 2, wherein said at least one section ofsaid flame path gap that extends substantially perpendicular to saidrotor shaft and said at least one section of said flame path gap thatextends substantially parallel to said rotor shaft have a combinedlength equal to or greater than a minimum length required to designate amotor an explosion proof motor.
 4. An explosion proof motor inaccordance with claim 2, wherein at least one of said flame path gapsections is non-linear.
 5. An explosion proof motor in accordance withclaim 1 further comprising at least one bearing assembly positionedbetween said end shield and said bearing cap.
 6. An explosion proofmotor in accordance with claim 5, wherein said bearing cap is positioneddirectly adjacent to said at least one bearing assembly.
 7. An explosionproof motor in accordance with claim 1, wherein said at least onesection of said flame path gap that extends substantially perpendicularto said rotor shaft extends from said end shield toward the interior ofsaid explosion proof motor.
 8. An explosion proof motor in accordancewith claim 1 further comprising two bearings of equal size positioned atopposite ends of said rotatable assembly.
 9. An explosion proof motor inaccordance with claim 1, wherein said at least one section of said flamepath gap that extends substantially parallel to said rotor shaft extendsinto said stator bore.
 10. An explosion proof motor in accordance withclaim 1, wherein said bearing cap has an outer radius that is less thanan inner radius of said stator bore.
 11. A method for assembling anexplosion proof motor, the explosion proof motor comprising a rotor anda rotor shaft positioned at least partially within an interior of astator bore, the rotor shaft extending axially through the stator bore,said method comprising; positioning a bearing cap around the rotorshaft; positioning a bearing around the rotor shaft and proximate to thebearing cap; and positioning an end shield proximate to the bearing andthe bearing cap, wherein a flame path gap is defined between the bearingcap and the end shield, the flame path gap comprising at least onesection that extends substantially parallel to said rotor shaft.
 12. Amethod in accordance with claim 11, wherein positioning the end shieldproximate to the bearing and the bearing cap comprises positioning theend shield proximate to the bearing cap to define a flame path gapfurther comprising at least one section that extends substantiallyperpendicular to said rotor shaft.
 13. A method in accordance with claim12, wherein positioning the end shield proximate to the bearing and thebearing cap comprises securing the end shield and the bearing cap inpositions along the rotor shaft to define at least one substantiallyradial section of the flame path gap that extends substantially radiallyoutward from the rotor shaft, and at least one substantially axialsection of the flame path gap that extends substantially axially towardthe stator bore interior.
 14. A method in accordance with claim 11further comprising positioning the bearing cap directly adjacent to thebearing.
 15. An end shield and inner bearing cap assembly for anexplosion proof motor, said assembly comprising: an end shield; an innerbearing cap, said inner bearing cap positioned proximate to said endshield, said end shield and said inner bearing cap comprising shaftopenings extending substantially axially therethrough; and a flame pathgap defined between said end shield and said inner bearing cap, saidflame path gap comprising at least one section that extendssubstantially parallel to said axial shaft openings.
 16. An end shieldand inner bearing cap assembly in accordance with claim 15, wherein saidflame path gap further comprises at least one section that extendssubstantially perpendicular to said axial shaft openings.
 17. An endshield and inner bearing cap assembly in accordance with claim 16,wherein at least one of said flame path gap sections is non-linear. 18.An end shield and inner bearing cap assembly in accordance with claim15, said assembly further comprising a bearing assembly pocketconfigured to secure a bearing assembly.
 19. An end shield and innerbearing cap assembly in accordance with claim 15, wherein said at leastone section of said flame path gap that extends substantially parallelto said rotor shaft extends into said stator bore.
 20. An end shield andinner bearing cap assembly in accordance with claim 15, wherein saidinner bearing cap has an outer radius that is less than an inner radiusof a stator bore of said motor.